The present invention relates to an electric motor, in particular to a DC motor.
The state of the art already discloses a certain number of electric motors comprising a coiled rotor whose windings are energized by way of a commutator, a stator comprising a cylindrical shell in which is disposed a brush-carrying ring in the vicinity of an end of the said shell, and an end flange fixed to the said end of the shell, the said flange being provided with a roller bearing receiving the rotor, the said ring supporting two electrical supply brushes each associated with an elastic pressure member, each of the brushes and the respective elastic member being displaceable between a standby position, prior to the complete assemblage of the motor, in which the brush is separated from the commutator, and a working position, in which the brush, via a contact face, bears on the commutator and the elastic member exerts a radial force on a supporting face of the brush, which face is opposite to the contact face tending to press the said brush onto the commutator.
However, these motors exhibit a certain number of drawbacks, especially when assembling the various components constituting the motor.
Specifically, the brushes must be placed in their working position, where they are pressed against the commutator, only when the assemblage phase is complete, so that the ring can be arranged around the commutator without the brushes rubbing on it. To do this, they are locked in a temporary manner in their standby position, then unlocked and placed in their working position when assemblage of the motor is complete.
The operation of displacing the brushes from their standby position to their working position requires the use of specific machines intended to apply, across the shell, an unlocking pressure on the brushes, or the prior installation of a ring for retaining the brushes in their standby position, this ring being removed when the mounting operation is complete.
These arrangements provided for on known electric motors are not entirely satisfactory on account of the cost of the unlocking machines, or of the cost of manufacturing the specially provided components for effecting the temporary locking of the brushes, and owing to the additional operation time which this represents.
In order to remedy the aforesaid drawbacks, the subject of the invention is an electric motor of the aforesaid type whose end flange comprises a projecting member corresponding to each brush, adapted so as to bear on the brush and displace the said brush and the respective elastic member from their standby position to their working position, when assembling the end flange onto the shell.
By virtue of this arrangement, the unlocking of the brushes and their movement from their standby position to their working position is achieved automatically when assemblage of the motor is complete, that is to say when the end flange is mounted on the shell.
This operation is achieved without additional tooling, with no additional component, and also without any operation time being added to the motor assemblage time.
According to other characteristics of the invention:
the assembling of the flange onto the shell is carried out by at least one axial relative motion, and the projecting member is an axial finger having a ramp intended to bear on an edge of the corresponding brush, and adapted so that the axial motion of assembling the flange causes a radial motion of the brush to its working position;
the assembling of the flange onto the shell is carried out by at least one rotary relative motion, and the projecting member is an axial finger having a ramp intended to bear on an edge of the corresponding brush, and adapted so that the rotary motion of assembling the flange causes a radial motion of the brush to its working position;
the flange is fixed onto the shell by means of a bayonet device;
the elastic member is a spiral spring comprising an end arm which, in the standby position, is axially disengaged from the supporting face and axially prestressed, so as to move axially into its working position upon the radial displacement of the brush;
the end arm bears, in the standby position, on a substantially radial face of the brush; and
the brush comprises a notch on its supporting face, said notch being adapted to be engaged by the end arm and retain said end arm, when the elastic member and the brush are in their working position.
The invention is also aimed at a drive device for motor vehicle equipment, comprising an electric motor as described above.